linux-kernel - Re: [PATCH 04/13] ibmvfc: add alloc/dealloc routines for SCSI Sub-CRQ Channels

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Message-ID: <0eeac30f-07bd-d4c5-fe21-d5092ca3fd62@linux.ibm.com>
Date:   Mon, 30 Nov 2020 09:26:05 -0800
From:   Tyrel Datwyler <tyreld@...ux.ibm.com>
To:     Brian King <brking@...ux.vnet.ibm.com>,
        james.bottomley@...senpartnership.com
Cc:     martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        brking@...ux.ibm.com
Subject: Re: [PATCH 04/13] ibmvfc: add alloc/dealloc routines for SCSI Sub-CRQ
 Channels

On 11/27/20 9:46 AM, Brian King wrote:
> On 11/25/20 7:48 PM, Tyrel Datwyler wrote:
>> Allocate a set of Sub-CRQs in advance. During channel setup the client
>> and VIOS negotiate the number of queues the VIOS supports and the number
>> that the client desires to request. Its possible that the final channel
>> resources allocated is less than requested, but the client is still
>> responsible for sending handles for every queue it is hoping for.
>>
>> Also, provide deallocation cleanup routines.
>>
>> Signed-off-by: Tyrel Datwyler <tyreld@...ux.ibm.com>
>> ---
>>  drivers/scsi/ibmvscsi/ibmvfc.c | 115 +++++++++++++++++++++++++++++++++
>>  drivers/scsi/ibmvscsi/ibmvfc.h |   1 +
>>  2 files changed, 116 insertions(+)
>>
>> diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
>> index 260b82e3cc01..571abdb48384 100644
>> --- a/drivers/scsi/ibmvscsi/ibmvfc.c
>> +++ b/drivers/scsi/ibmvscsi/ibmvfc.c
>> @@ -4983,6 +4983,114 @@ static int ibmvfc_init_crq(struct ibmvfc_host *vhost)
>>  	return retrc;
>>  }
>>  
>> +static int ibmvfc_register_scsi_channel(struct ibmvfc_host *vhost,
>> +				  int index)
>> +{
>> +	struct device *dev = vhost->dev;
>> +	struct vio_dev *vdev = to_vio_dev(dev);
>> +	struct ibmvfc_sub_queue *scrq = &vhost->scsi_scrqs.scrqs[index];
>> +	int rc = -ENOMEM;
>> +
>> +	ENTER;
>> +
>> +	scrq->msgs = (struct ibmvfc_sub_crq *)get_zeroed_page(GFP_KERNEL);
>> +	if (!scrq->msgs)
>> +		return rc;
>> +
>> +	scrq->size = PAGE_SIZE / sizeof(*scrq->msgs);
>> +	scrq->msg_token = dma_map_single(dev, scrq->msgs, PAGE_SIZE,
>> +					 DMA_BIDIRECTIONAL);
>> +
>> +	if (dma_mapping_error(dev, scrq->msg_token))
>> +		goto dma_map_failed;
>> +
>> +	rc = h_reg_sub_crq(vdev->unit_address, scrq->msg_token, PAGE_SIZE,
>> +			   &scrq->cookie, &scrq->hw_irq);
>> +
>> +	if (rc) {
>> +		dev_warn(dev, "Error registering sub-crq: %d\n", rc);
>> +		dev_warn(dev, "Firmware may not support MQ\n");
>> +		goto reg_failed;
>> +	}
>> +
>> +	scrq->hwq_id = index;
>> +	scrq->vhost = vhost;
>> +
>> +	LEAVE;
>> +	return 0;
>> +
>> +reg_failed:
>> +	dma_unmap_single(dev, scrq->msg_token, PAGE_SIZE, DMA_BIDIRECTIONAL);
>> +dma_map_failed:
>> +	free_page((unsigned long)scrq->msgs);
>> +	LEAVE;
>> +	return rc;
>> +}
>> +
>> +static void ibmvfc_deregister_scsi_channel(struct ibmvfc_host *vhost, int index)
>> +{
>> +	struct device *dev = vhost->dev;
>> +	struct vio_dev *vdev = to_vio_dev(dev);
>> +	struct ibmvfc_sub_queue *scrq = &vhost->scsi_scrqs.scrqs[index];
>> +	long rc;
>> +
>> +	ENTER;
>> +
>> +	do {
>> +		rc = plpar_hcall_norets(H_FREE_SUB_CRQ, vdev->unit_address,
>> +					scrq->cookie);
>> +	} while (rc == H_BUSY || H_IS_LONG_BUSY(rc));
>> +
>> +	if (rc)
>> +		dev_err(dev, "Failed to free sub-crq[%d]: rc=%ld\n", index, rc);
>> +
>> +	dma_unmap_single(dev, scrq->msg_token, PAGE_SIZE, DMA_BIDIRECTIONAL);
>> +	free_page((unsigned long)scrq->msgs);
>> +	LEAVE;
>> +}
>> +
>> +static int ibmvfc_init_sub_crqs(struct ibmvfc_host *vhost)
>> +{
>> +	int i, j;
>> +
>> +	ENTER;
>> +
>> +	vhost->scsi_scrqs.scrqs = kcalloc(vhost->client_scsi_channels,
>> +					  sizeof(*vhost->scsi_scrqs.scrqs),
>> +					  GFP_KERNEL);
>> +	if (!vhost->scsi_scrqs.scrqs)
>> +		return -1;
>> +
>> +	for (i = 0; i < vhost->client_scsi_channels; i++) {
>> +		if (ibmvfc_register_scsi_channel(vhost, i)) {
>> +			for (j = i; j > 0; j--)
>> +				ibmvfc_deregister_scsi_channel(vhost, j - 1);
>> +			kfree(vhost->scsi_scrqs.scrqs);
>> +			LEAVE;
>> +			return -1;
>> +		}
>> +	}
>> +
>> +	LEAVE;
>> +	return 0;
>> +}
>> +
>> +static void ibmvfc_release_sub_crqs(struct ibmvfc_host *vhost)
>> +{
>> +	int i;
>> +
>> +	ENTER;
>> +	if (!vhost->scsi_scrqs.scrqs)
>> +		return;
>> +
>> +	for (i = 0; i < vhost->client_scsi_channels; i++)
>> +		ibmvfc_deregister_scsi_channel(vhost, i);
>> +
>> +	vhost->scsi_scrqs.active_queues = 0;
>> +	kfree(vhost->scsi_scrqs.scrqs);
> 
> Do you want to NULL this out after you free it do you don't keep
> a reference to a freed page around?

This isn't actually a page, but a dynamically allocated array of
ibmvfc_sub_queues, but it should be NULL'ed regardless.

-Tyrel

> 
>> +	LEAVE;
>> +}
>> +
>>  /**
>>   * ibmvfc_free_mem - Free memory for vhost
>>   * @vhost:	ibmvfc host struct
> 
> 
>